1. Field of the Invention
The present invention relates to a refrigerator, and more particularly, to a refrigerator and a method for keeping food fresh using the same, in which freshness is maintained for a long time through an improved structure and decrease of nutritive elements contained in the food is inhibited.
2. Discussion of the Related Art
Generally, a refrigerator includes a freezing chamber and a refrigerating chamber. The refrigerating chamber is provided with a separate vegetable compartment that serves to keep vegetables and fruits more freshly by controlling humidity. Hereinafter, vegetables and fruits will be referred to as “vegetables.” Accordingly, the vegetable compartment inside the refrigerating chamber may be an example of a food container.
Temperature, humidity, environmental gas, microbe, and light are known as main factors that deteriorate freshness of vegetables. Since vegetables continue to breathe and transpire, it is essentially required that breathing and transpiration should be inhibited to maintain freshness of the vegetables. Specifically, most of the vegetables excluding some vegetables that cause disorder at a low temperature can be inhibited from breathing at a low temperature and can be prevented from transpiring at high humidity.
In this respect, a general refrigerator for home use includes a food container which serves as a separate space independent of a refrigerating chamber and is only used to keep vegetables, so that the vegetables can be maintained with freshness for a long time. The food container maintains vegetables at a proper low temperature and at the same time controls humidity using water transpired from the vegetables. Accordingly, the vegetables can be maintained with freshness for a long time by the food container.
Meanwhile, methods for maintaining freshness of vegetables for a long time by using light have been recently suggested.
Strong light adversely affects food in such a way to expedite discoloration and transpiration of the food. On the other hand, it is known that relatively weak light serves to improve freshness of vegetables. It is also known that such weak light inhibits decomposition of chlorophyll in green vegetables and effectively maintains vitamin C.
Hereinafter, a related art refrigerator having a food container will be described with reference to FIG. 1.
FIG. 1 illustrates a top mount type refrigerator in which a freezing chamber is disposed at a top portion and a refrigerating chamber is disposed below the freezing chamber.
The related art refrigerator is disclosed in Japanese Patent Publication Pyung9-28363. Referring to FIG. 1, this related art refrigerator 10 includes a drawer type food container 20 provided at a lower portion and an irradiation device 23 irradiating weak light to the food container 20, to prevent reduction in the concentration of chlorophyll in green vegetables, and prevent deterioration in quality of the green vegetables.
In particular, the refrigerator 10 is designed such that a lamp 29 is operated to allow a user to recognize an object in a keeping compartment 21 when the drawer type food container is opened while the irradiation device 23 is operated to prevent quality of green vegetables from being deteriorated due to light when the drawer type food container is closed.
Meanwhile, Japanese Patent Publication No. Pyung 11-159953 discloses an irradiation device comprised of a light emitting diode (LED) of a visible ray area to minimize emission of heat caused by the irradiation device, whereby a temperature in a keeping compartment is prevented from increasing and the irradiation device is driven at higher efficiency than other irradiation devices.
Furthermore, Japanese Patent Publication No. 2005-49093 discloses a red LED having a wavelength of 660 nm applied to green vegetables.
Moreover, Japanese Patent Publication No. 2005-65622 discloses an irradiation device that irradiates light of a proper wavelength depending on kinds of vegetables by dividing a food container into a plurality of keeping compartments. In more detail, this related art discloses three LEDs of red, green and blue to select combination of light-emitting colors depending on kinds of vegetables.
However, the related art food container has several problems.
First, although the related art irradiation device can select combination of light-emitting colors through the three-colored LEDs of red, green and blue, it is not apparent for what food the LEDs are effective. For this reason, the irradiation device is little effective in maintaining freshness of food or preventing chlorophyll from being reduced.
Second, it is not apparent that various kinds of foods should be kept separately in a plurality of keeping compartments based on which classification standard even though the food container is divided into the plurality of keeping compartments. Accordingly, there is no effectiveness that can be obtained as the food container is divided into a plurality of keeping compartments.
Third, although there is provided a selecting means for selecting light-emitting colors of the three-colored LEDs, the selecting means has little effectiveness as it is impossible to identify what a light-emitting color of light suitable for a specific food is.
Even though it is possible to identify a light-emitting color depending on kinds of foods through experiments, there exists inconvenience in that a user should remember or search such information of light emitting colors to select a light-emitting color of irradiated light.
Fourth, problems relating to reliability of the irradiation device occur in that the user cannot determine whether to select which light-emitting color for a food which is not identified by experiments and that the user cannot identify whether its selected light-emitting color is suitable for a corresponding food.
Fifth, although the user can select a light-emitting color obtained by combination of three colors from the three-colored LEDs, the selected light-emitting color is uniformly irradiated to various kinds of foods in spite of the fact that an effective light-emitting color depends on kinds of the foods. For this reason, if various kinds of foods are kept in the keeping compartments, freshness of every food is not maintained uniformly.
Sixth, a light source of a vegetable box is always turned on regardless of the presence of vegetables. Also, since an LED used as the light source in the vegetable box of the refrigerator has power consumption in the range of 0.1 W to 1 W, unnecessary power consumption occurs if the light source continues to be turned on.
Seventh, heat is emitted inevitably if the light source is turned on. In this case, a problem occurs in that a temperature of the vegetable box and/or the refrigerating chamber increases.
Finally, a problem occurs in that the related art food container may decay fruits or quickly wither vegetables due to ethylene generated from the food kept therein.